Suffolk County drilled the first two of nine monitoring wells at Roberto Clemente Park in Brentwood Tuesday to test whether the groundwater under the park has been affected by the contaminated fill dumped there.

The drilling and sampling by the county's Department of Health Services will take two to four weeks to complete, and results of the tests will come back in six to eight weeks, according to health commissioner James Tomarken.

The department had outlined its testing plan in a Jan. 16 report to the Suffolk County Legislature, which passed a resolution in December directing the department to begin testing at the park and consider testing at the three other sites where the Suffolk County district attorney said contaminated fill had been dumped.

Those sites are: a vacant lot at the corner of Sage Street and Islip Avenue in Central Islip; a six-home development for war veterans in Islandia; and a state-protected wetlands area in Deer Park.

The health department plans to continue drilling Wednesday.

Tomarken said an agreement that allowed the county access to the park, owned by the Town of Islip, was signed on Feb. 23 -- more than a month after the town board voted to allow the county onto the property -- but weather conditions delayed the drilling for an additional 2 1/2 weeks.

"I am elated to know the drilling started," said Legis. Monica R. Martinez (D-Brentwood), who sponsored the resolution along with legislators Kara Hahn (D-Setauket) and Thomas Barraga (R-West Islip). "The weather definitely did not help."

Islip Town did not respond to requests for comment.

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Nine temporary wells will be drilled within the park at depths ranging from 50 to 75 feet, with additional wells off-site to determine the direction of underground water flow, according to the report.

Three monitoring wells the town installed last year at the park showed lead in the groundwater south of the park's recharge basin and soccer fields, but the metal wasn't found north of where the estimated 50,000 tons of contaminated fill was dumped.

While the town's consultant, Enviroscience Consultants Inc., said the results showed groundwater hadn't been significantly impacted from the fill, the health department, examining the same data, said additional tests were needed.

The nearest public-supply well is more than a mile away from the park, according to the health department, and all water supplied to the public is treated to meet drinking-water standards.

Brentwood activist Nelsena Day of Suffolk County's chapter of New York Communities for Change said the results of the county's testing will help answer some pressing questions.

"Is this stuff moving? Is it going further down? Is it really going into the aquifer?" she said. "Hopefully, we're going to get all of this stuff cleared up."